Same thing happened to me, but I think they have so much work that they cannot do all this...
What you should try to do is to cancel that order put in other coin and try to withraw that coin down from poloniex...
The thing is that there could be also some problem with your coins, adress you sended, etc...
For me the thing happened like this(but also like 2-3 month back...) I tryed to withraw 150$ in some currency, but I inserted wrong adress(lucky me was 1 letter less so poloniex didn't even send those coins) After a while(when I thought I lost all those coins, I went to look on history page, and there was that withrawal still with cancel option, so i canceled, and tryed to withraw with real adress, but also after 1 day still pending... so I wrote a ticket, but after 3-6 day still nothing I took things in my hands, so I sold those currency that wouldn't withraw, Bought digibytes, sended digybytes to other cryptocurrency exchange, and there bought those that I needed...
gl to you all, I don't store more than 2k on exchanges, probobly because I don't have much atm.